class MemCache::Server

This class represents a memcached server instance.

Constants

RETRY_DELAY

The amount of time to wait before attempting to re-establish a connection with a server that is marked dead.

Attributes

host[R]

The host the memcached server is running on.

logger[R]
port[R]

The port the memcached server is listening on.

retry[R]

The time of next retry if the connection is dead.

status[R]

A text status string describing the state of the server.

weight[R]

The weight given to the server.

Public Class Methods

new(memcache, host, port = DEFAULT_PORT, weight = DEFAULT_WEIGHT) click to toggle source

Create a new MemCache::Server object for the memcached instance listening on the given host and port, weighted by the given weight.

# File lib/memcache.rb, line 1003
def initialize(memcache, host, port = DEFAULT_PORT, weight = DEFAULT_WEIGHT)
  raise ArgumentError, "No host specified" if host.nil? or host.empty?
  raise ArgumentError, "No port specified" if port.nil? or port.to_i.zero?

  @host   = host
  @port   = port.to_i
  @weight = weight.to_i

  @sock   = nil
  @retry  = nil
  @status = 'NOT CONNECTED'
  @timeout = memcache.timeout
  @logger = memcache.logger

  if defined?(EM) and EM.reactor_running? and defined?(MemCache::EventedServer)
    self.extend(MemCache::EventedServer)
  end
end

Public Instance Methods

alive?() click to toggle source

Check whether the server connection is alive. This will cause the socket to attempt to connect if it isn't already connected and or if the server was previously marked as down and the retry time has been exceeded.

# File lib/memcache.rb, line 1035
def alive?
  !!socket
end
close() click to toggle source

Close the connection to the memcached server targeted by this object. The server is not considered dead.

# File lib/memcache.rb, line 1099
def close
  @sock.close if @sock && !@sock.closed?
  @sock   = nil
  @retry  = nil
  @status = "NOT CONNECTED"
end
connect_to(host, port, timeout=nil) click to toggle source
# File lib/memcache.rb, line 1065
def connect_to(host, port, timeout=nil)
  sock = nil
  if timeout
    MemCacheTimer.timeout(timeout) do
      sock = TCPSocket.new(host, port)
    end
  else
    sock = TCPSocket.new(host, port)
  end

  io = MemCache::BufferedIO.new(sock)
  io.read_timeout = timeout
  # Getting reports from several customers, including 37signals,
  # that the non-blocking timeouts in 1.7.5 don't seem to be reliable.
  # It can't hurt to set the underlying socket timeout also, if possible.
  if timeout
    secs = Integer(timeout)
    usecs = Integer((timeout - secs) * 1_000_000)
    optval = [secs, usecs].pack("l_2")
    begin
      io.setsockopt Socket::SOL_SOCKET, Socket::SO_RCVTIMEO, optval
      io.setsockopt Socket::SOL_SOCKET, Socket::SO_SNDTIMEO, optval
    rescue Exception => ex
      # Solaris, for one, does not like/support socket timeouts.
      @logger.info "[memcache-client] Unable to use raw socket timeouts: #{ex.class.name}: #{ex.message}" if @logger
    end
  end
  io
end
inspect() click to toggle source

Return a string representation of the server object.

# File lib/memcache.rb, line 1025
def inspect
  "<MemCache::Server: %s:%d [%d] (%s)>" % [@host, @port, @weight, @status]
end
mark_dead(error) click to toggle source

Mark the server as dead and close its socket.

# File lib/memcache.rb, line 1109
def mark_dead(error)
  close
  @retry  = Time.now + RETRY_DELAY

  reason = "#{error.class.name}: #{error.message}"
  @status = sprintf "%s:%s DEAD (%s), will retry at %s", @host, @port, reason, @retry
  @logger.info { @status } if @logger
end
socket() click to toggle source

Try to connect to the memcached server targeted by this object. Returns the connected socket object on success or nil on failure.

# File lib/memcache.rb, line 1043
def socket
  return @sock if @sock and not @sock.closed?

  @sock = nil

  # If the host was dead, don't retry for a while.
  return if @retry and @retry > Time.now

  # Attempt to connect if not already connected.
  begin
    @sock = connect_to(@host, @port, @timeout)
    @sock.setsockopt Socket::IPPROTO_TCP, Socket::TCP_NODELAY, 1
    @retry  = nil
    @status = 'CONNECTED'
  rescue SocketError, SystemCallError, IOError, Timeout::Error => err
    logger.warn { "Unable to open socket: #{err.class.name}, #{err.message}" } if logger
    mark_dead err
  end

  return @sock
end